Computerized Tomography–Based Morphometric Analysis of Odontoid in 100 Egyptian Patients

Abstract

Background: There is still no consensus in the literature regarding the use of 1 screw or 2 screws. A number of studies have proved ethnic variations in the morphometry of the odontoid. There is no literature on the morphometry of odontoid in Egyptian patients. Methods: Computerized tomography (CT) scans of the head and cervical spine of 100 healthy (no evidence of cervical spine fracture) patients of Egyptian origin were studied. Measurements were performed using Horos software, which allowed exact morphometric measurements to be taken at a specific angle in the axial, coronal, and sagittal planes. Results: The mean age was 48.57 6 15.39 years (range, 18-79 years; 56 male and 44 female patients). The mean radiologically calculated screw length and the mean radiologically calculated screw insertion angle were 38.21 6 2.2 mm and 55.78 6 3.848, respectively. The mean anteroposterior and transverse diameter of the odontoid at the waist in the axial cut were 11.02 6 1.05 mm and 8.92 6 0.93 mm, respectively. A total of 54% and 6% of the study sample had the transverse waist diameter of the odontoid in the axial cut below 9 mm and 7.4 mm, respectively. A total of 48% of the male and 61% of the female patients had their transverse diameter of the odontoid at the waist below 9 mm. There was a statistically significant difference in all the measurements of the odontoid between the male and female patients except in the anteroposterior diameter of the base of odontoid (P ¼ .06) in the axial cut, and the radiologically calculated screw insertion angle (P ¼ .57). The mean distance between the apex of the odontoid and the screw exit was 1.8 6 0.75 mm (range, 0-3 mm). Conclusions: CT-based morphometric analysis of the odontoid is necessary before using 2-screw fixation technique. Single 4.5-mm Herbert screws could be used in all Egyptian patients without the need for CT-based morphometric analysis of the odontoid. The posterior screw can violate the posterior wall of the odontoid, with a reduced fracture hold and a chance of injuring the thecal sac.

A Radiological Study of the Morphological Variations in the Odontoid Process of the Axis Vertebra, Benghazi

“…It was detected in 24 male (24/39) and 15 female (15/39) patients and Type II was recorded in 73 cases (65.2%). It was depicted in 44 male (44/73) and 29 female (29/73) patients and a higher prevalence in the ≤30y age group were pyramidal while the oval type showed a higher prevalence in the >30 age group (statistically significant differences) (23)(24)(25)(26)(27) . Regarding the morphological variants of the dens: In the present study we found one variant (persistent ossiculumterminale) among the sample in contrast to Perdikakis et al (2012) in their study on a Greek population retrospectively reviewing 112 patients who found an osterminale could be identifiable (with different degrees of ossification and fusion) in 22 cases (22-26-27) .…”